The year is 1956. Sister June, a young nun who has barely ever left her convent, is ordered to travel to a remote Swiss castle. There, she discovers that the mysterious Father Ravenscroft and his assistant have begun a deadly experiment. Something is lurking in the depths of the castle. Something has been captured and chained up, ready to be examined. Whatever it is, this 'thing' is desperate to be free and begs June to show mercy. She trusts her superiors and refuses to intervene, even when she hears cries of agony coming from the torture chamber, but is her faith in Father Ravenscroft misplaced? As a snowstorm threatens to destroy the castle, a deadly force prepares to show its hand. Will June discover the truth in time, or is she destined to become nothing more than a pawn in a game that has been running for centuries?